1. Field of the Invention
The present invention relates to manufacturing techniques of a display device such as a liquid crystal display device, and, in particular, to a technique for inspecting sealing at a liquid crystal injection port of a liquid crystal panel.
2. Description of the Related Art
A liquid crystal panel is manufactured by injecting a liquid crystal material between two glass substrates. In a common manufacturing method of a liquid crystal panel, electrode patterns and an alignment film are formed on each of the two glass substrates and then a sealing material and spacers are disposed therebetween. Subsequently, the substrates are assembled together, whereby liquid crystal cells are formed. Then, liquid crystal is injected into the liquid crystal cells defined by the sealing material and then an injection port is sealed. In this way, a liquid crystal panel is manufactured.
In the above-described manufacturing method of a liquid crystal panel, the liquid crystal is generally injected by a vacuum injection method, and, after the injection of the liquid crystal, sealing resin such as an ultraviolet cure resin is applied in the vicinity of a liquid crystal injection port and irradiated with ultraviolet for curing the sealing resin to seal the liquid crystal injection port.
In the process for sealing the liquid crystal injection port, if, for example, the sealing resin is not completely cured or the sealing resin contains impurities, the uncured sealing material or the impurities would tend to gradually diffuse into the liquid crystal. And in a portion where the uncured sealing material or the impurities is/are diffused, of the liquid crystal panel, characteristics such as voltage-transmittance or specific resistance would be deteriorated. The deteriorated characteristics of the liquid crystal would lead to a degradation of display performance or local variation of luminance (luminance unevenness in the injection port) in the vicinity of the injection port of the liquid crystal panel. Accordingly, it is required to completely cure the sealing resin in the process for sealing the liquid crystal injection port.
For example, Patent Literature 1 discloses a liquid crystal display device in which a sealing material having invaded between a pair of glass substrates is cured so that the uncured part is not remained, in order to avoid a display failure resulting from the uncured sealing material. Particularly, a transmission section through which ultraviolet or a visible light can transmit is provided in light shielding films or wires in the vicinity of the injection port on at least one substrate, and the sealing material is sufficiently irradiated with ultraviolet or visible light transmitted through the transmission section. Therefore, the sealing material in the injection port is cured.